The liquid crystal display (hereinafter, referred to as LCD) which is most widely used at present is a twisted nematic LCD (hereinafter, referred to as TN-LCD) of which type is normally white (hereinafter, referred to as NW) mode in which a liquid crystal cell (such that nematic liquid crystal is held between a pair of glass substrates having transparent electrodes) is sandwiched between a pair of linearly polarizing films disposed so that the absorption axes thereof are perpendicular to each other. The nematic liquid crystal has an orientation structure such that the helical axis is normal to the glass substrates and the twist angle thereof is approximately 90 degrees.
When no voltage is applied, the NW mode TN-LCD is in white state since the incident linearly polarized light exits after being rotated 90 degrees because of the optical rotatory power of the liquid crystal cell. When a voltage is applied, the NW mode TN-LCD is in black state since the liquid crystal molecules stand up with respect to the glass substrates to cause the optical rotatory power to disappear and the incident linearly polarized light exits as it is. Gray scale is performed by using the white state, the black state and intermediate states therebetween.
However, the nematic liquid crystal used for the LCD has a rod-like molecular structure and exhibits positive refractive index anisotropy where the refractive index is higher in the direction of the molecular axis than in the normal direction to the molecular axis, so that the polarization condition of light obliquely passing through the liquid crystal cell varies in a different direction from a normal direction to the liquid crystal cell because of a phase difference due to the refractive index anisotropy of the liquid crystal. For this reason, when the display on the LCD is viewed from angles other than a normal direction to the LCD, viewing angle characteristics are shown such that the contrast decreases and that gray scale inversion takes place.
Since the viewing angle characteristics are caused by the refractive index anisotropy of the liquid crystal molecules, an improvement is being examined using a phase retarder film exhibiting a refractive index anisotropy opposite to that of the liquid crystal to compensate the phase difference due to the refractive index anisotropy of the liquid crystal molecules.
However, only a phase retarder film can be obtained that has small size, or is heavy in weight, or is inferior in mass production.
In view of circumstances, the present inventors have developed a phase retarder film having large size, being light-weight and being excellent in mass productivity which comprises an oblique evaporation layer comprising an inorganic dielectric such as Ta.sub.2 O.sub.5, WO.sub.3 and SiO.sub.2.